and rumors have swirled around kate middleton. mark phillips with an announcement today from the palace. captioning sponsored by cbs this is the "cbs evening news" with scott pelley. >> pelley: good evening. president obama sent a sharp warning today to bashar al-assad the syrian dictator who is fighting a rebellion by his own people. assad has not used his chemical weapons, including nerve gas, but the possibility that he might threatens to pull the united states into that middle east conflict. here's how mr. obama put it. >> i want to make it absolutely clear to assad and those under his command. the world is watching. the use of chemical weapons is and would be totally unacceptable. and if you make the tragic mistake of using these weapons, there will be consequences and you will be held accountable. >> pelley: so why did the president say it today? david martin hat the pentagon has been talking to his sources. >> reporter: this is a commercial satellite photo of a syrian chemical weapons base. u.s. monitoring of roughly two do